Stimuli-Responsive Metal–Organic Framework on a Metal–Organic Framework Heterostructure for Efficient Antibiotic Detection and Anticounterfeiting

Stimuli-responsiveness
is an important characteristic that show
promising potential in various applications. Herein, a novel ZIF-8-on-Tb-dpn
(H3dpn = 5-(2′,4′-dicarboxylphenyl)­nicotic
acid) heterostructure is constructed using a heteroepitaxial strategy
combining the chemical-responsive (antibiotics) and light-responsive
behaviors. The pyridine nitrogen of Tb-dpn acts as an anchor site
for Zn2+, which helps to overcome the limit of lattice
mismatch between two metal–organic frameworks (MOFs) and promotes
the growth of ZIF-8 nanocrystals. Based on the synergy effect of two
MOFs, ZIF-8-on-Tb-dpn exhibits an efficient turn-off response toward
tetracycline and chloramphenicol via competitive absorption, Förster
resonance energy transfer, and photoinduced electron transfer processes
with limit of detection values of 5.6 and 37.6 nM, respectively, which
are three- to −fivefold lower than those of Tb-dpn. Moreover,
the nanocage of ZIF-8 is utilized to encapsulate photochromic spiropyran
(SP) molecules and realize the reversible conversion between SP and
merocyanine (MC) under visible light and ultraviolet light. The MC
form is accompanied with strong adsorption at 555 nm, which can erase
the emission of Tb3+. Therefore, a reversible invisible
anticounterfeiting pattern is designed with SP ⊂ ZIF-8-on-Tb-dpn
for information anticounterfeiting. The excellent stimuli-responsive
ability makes the luminescent platform a potential candidate in luminescence
applications.